1. Field of the Invention
This invention relates to a horizontal double disc surface grinding machine.
2. Description of the Related Art
Conventionally, as a horizontal double disc surface grinding machine, a grinding machine of through-feed type, in which a work is made continuously and linearly pass between facing flat faces of grinding wheels, is known (refer to Japanese Patent Provisional Publication NO. S60-259364).
For example, a horizontal double disc surface grinding machine, a grinding machine of through-feed type as shown in a top view of FIG. 14 and an enlarged explanatory view of a principal portion of FIG. 15, is known.
A pair of left and right endless V-belts, holding and giving feed F0 to a plate work 32 such as a circular plate and a ring plate in vertical posture, and, a pair of left and right straight work guiding plates 35, receiving the work 32 with the vertical posture on a downstream side of the V-belts 33 and guiding the work 32 between the grinding wheels 34, are provided.
Each of the V-belts 33 is suspended on a driving roller 36 and a following roller 37, and the V-belt 33 is moved in an arrow F33 direction by rotation of the driving roller 36 in an arrow M36 direction. As clearly shown in FIG. 14, parallel running portions 33A of the left and right V-belts 33 hold the work 32 and give the feed to the work 32 in the arrow F33 direction in mutually approximate state, the V-belts 33 are separated each other along the rotation of the rollers 36 after going over a straight line L1 connecting axis points L36 of the rollers 36.
Although the work guiding plate 35 is disposed with insertion within an approximately triangular area where the V-belts 33 are separated each other, a relatively large gap has to be formed between an upstream end 35A of the work guiding plate 35 and the V-belt 33 for the running of the V-belt 33, dimensional tolerance of the V-belt 33, vibration, etc. Therefore, a work transfer area Z from the V-belt 33 to the plate 35 is formed rather large in top view, the work 32 may be inclining and falling as shown in FIG. 15 in the transfer area Z (when the outline of the work 32 is small), stopped by the upstream end 35A of the guiding plate 35, and not transferred to the guiding plate 35 (this is called transfer anomaly in some cases).
When the above-mentioned transfer anomaly is generated, facility (the grinding machine) must be temporarily stopped, and working ratio of the facility is decreased. Further, in the case of the facility stop, although the work left between (the left and right) grinding wheels is ground again when the facility is re-started, working accuracy is not stable and working defects ratio is increased.
Therefore, it is an object of the present invention to provide a grinding machine in which the transfer from the V-belt to the guiding plate is conducted stably and smoothly (preventing the falling and stopping of the work) even if the work is small, the facility stop along the conventional transfer anomaly is prevented, working ratio of the facility is increased, and the defect generation ratio of the working accuracy is reduced.